Casting steel ball

【Introduction】:

Casting steel ball (casting grinding ball) is made of the scrap steel, scrap metal and other waste scrap which is melted by the heating of intermediate frequency electric furnace. In the melting process, the amount of precious metal alloy (such as iron, manganese, vanadium etc.) is added into the furnace for chemical composition. Then pour the qualified molten iron into the production line mold of steel ball when temperature of molten iron reaches more than 1550℃and the molten iron meets other technology requirements.

Notes:1. The ball with diameter 100mm is used in impact fatigue test; the test height is 3.5m; the impact times of the ball with other diameter are calculated by this formula, Nx=N*100/D, N is time.2. The impact toughness and impact fatigue life index is not treated as delivery basis.

Surface Quality

1. It is not allowed that crack, obvious porosity, slag inclusion, shrinkage, cold insulation, wrinkled skin and other casting defects exist on the surface.

2.Allowed defects on ball surface

Nominal Diameter

Allowed Surface Defects mm

Spare Part on Gate

Sand Dipping Area

Residual Side

Depth

Single Hole Area

Total Area

20—35

1.5

16

1.5

1.5

12

25

40—60

2.0

25

2.0

2.0

16

35

70—100

2.5

36

3.0

2.5

20

50

Internal quality

It is not allowed that crack, obvious porosity, slag inclusion, shrinkage, cold insulation, wrinkled skin and other casting defects exist on the section which goes through center of gate and sphere.

Test Method and Rules

1.Impact test: cutting 10mm×10mm×55mm part through gate in ball as sample

2.Rockwell hardness specimen preparation: The surface of the ball takes the test after grinding to platform, and the grinded thickness is 1.5 – 5mm.

3. Chemical composition test: when the volume smelting furnace more than 0.5 tons, we should check the chemical composition furnace by furnace; when the volume smelting furnace not more than 0.5 tons, we should check the chemical composition once per shift. Once there is one furnace unqualified, we need to sample double furnace for test. If there is still one not qualified, this branch of balls is unqualified.

4. Surface hardness test: sampling from different location of each batch of heating furnace, the number of the ball≥ 5.Once there is one unqualified, we need to sample double balls for test. If there is still a ball not qualified, this branch of balls is unqualified.

5. Internal quality detection: we sample 1 largest size casting iron grinding ball in 100 tons the same type cast iron grinding ball of each continuous production. Once there is one unqualified, we need to sample double balls for test. If there is still a ball not qualified, this branch of balls is unqualified.